Exchange apparatus

ABSTRACT

A heat exchanger comprising hollow thermoplastic tubes, which are fusion bonded with a thermoplastic resin to form unified terminal end blocks ( 32, 34 ), is disclosed. The hollow tubes may be shaped by plaiting or braiding the tubes into cords ( 70, 72 ) and then thermally annealing the cords ( 70, 72 ) to set the crests and bends of the plait or braid. The cords ( 70, 72 ) provide improved flow distribution of fluid about the hollow tubes in the heat exchanger. The heat exchanger is chemically inert and is useful for cross-flow filtration, as well as for heat- and mass-transfer applications in harsh chemical environments.

RELATED APPLICATIONS

This application claims the benefit of provisional application Ser. No.60/326,234 filed Oct. 1, 2001 entitled Fluid Exchange Device. Thisapplication is related to co-pending application filed concurrentlyherewith as U.S. Ser. No. 60/326,357, filed Oct. 1, 2001 underApplicants' reference number 200100293 (formerly MYKP-621).

FIELD OF INVENTION

This invention relates to a hollow tube or hollow fiber membraneexchange apparatus useful for heat transfer, particle filtration, andmass transfer applications. The apparatus comprises a housing containingfusion bonded hollow tubes that have been previously plaited andthermally annealed to set the plait. The apparatus has a high packingdensity of hollow tubes with enhanced fluid flow distribution providedby the plaited hollow tubes. The apparatus provides high contacting areain a small volume without the need for baffles. The device is made fromchemically inert thermoplastic materials and has the ability to operateat elevated temperatures with organic as well as corrosive and oxidizingliquids.

BACKGROUND

Hollow fibers and thin walled hollow tubes are commonly used in masstransfer, heat exchange, and cross flow particle filtration devices. Inthese applications the hollow tubes or fibers provide a high surface tovolume ratio which permits a greater transfer of heat and mass in asmaller volume than a device made with flat sheet materials of similarcomposition.

A hollow fiber or a hollow tube comprises an outer diameter and surface,an inner diameter and surface, and a porous or non-porous materialbetween the first and second surfaces or sides of the tube or fiber. Theinner diameter defines the hollow portion of the fiber or tube and isused to carry one of the fluids. For what is termed tube sidecontacting, a first fluid phase flows through the hollow portion,sometimes called the lumen, and is maintained separate from a secondfluid phase, which surrounds the tube or fiber. In shell sidecontacting, the first fluid phase surrounds the outer diameter andsurface of the tube or fibers and the second fluid phase flows throughthe lumen. In an exchange apparatus, packing density relates to thenumber of useful hollow fiber or hollow tubes that can be potted in theapparatus.

Examples of applications in semiconductor manufacturing where heating ofa liquid is required include sulfuric acid and hydrogen peroxidephotoresist strip solutions, hot phosphoric acid for silicon nitride andaluminum metal etching, ammonium hydroxide and hydrogen peroxide SC1cleaning solutions, hydrochloric acid and hydrogen peroxide SC2 cleaningsolutions, hot deionized water rinses, and heated organic amine basedphotoresist strippers.

Cooling of heated liquids after use in a bath, especially photoresiststripping solutions, phosphoric acid, SC1 and SC2 cleaning solutions isnecessary prior to disposing of the used chemical. Electrochemicalplating baths and apparatus are sometimes maintained at sub-ambienttemperatures.

On a wafer processing track apparatus, accurate and repeatableconditioning of the temperature of liquids such as spin on dielectrics,photoresists, antireflective coatings, and developers prior to dispenseonto a wafer requires heating or cooling of these liquids.

Heat exchangers are devices which transfer heat from one fluid, theprocess fluid, and a second working fluid. Polymer based heat exchangersare used for heating and cooling chemicals for these applications due totheir chemical inertness and resistance to corrosion. However, polymericheat exchange devices are usually large because a high heat transfersurface area is required to effect a given temperature change due to thelow thermal conductivity of the polymers used in the device. Braiding ofthe tubes is used prevent the tubes from becoming unevenly spaced whenused in open container heat exchange applications. Such devices take upvaluable space, requires large holdup volumes of chemicals or exchangefluid, and are costly to make. Such devices also require o-ring sealswhich are prone to failure and are also a source of ionic andparticulate contamination.

Quartz heaters are also used to heat liquids used for semiconductorprocessing. Quartz is susceptible to breakage and exposed resistivelyheated surfaces pose fire and explosion hazards especially for organicliquids and liquids which evolve flammable gases.

Gas to liquid contactors or exchangers using hollow fiber tubes are usedin semiconductor manufacturing to remove or to add gases to liquids.Commercially available gas to liquid contactors utilize baffles toimprove mass transfer between the fluids. Typical applications forcontacting membrane systems are to remove dissolved gases from liquids,“degassing”, or to add a gaseous substance to a liquid. For example, awet bench is a wafer processing apparatus where ozone gas is added tovery pure water to be contacted with semiconductor wafers for cleaningand oxide growth.

Cross flow filtration is used in semiconductor manufacturing to removesuspended solids, such as abrasive particles used in chemical mechanicalpolishing slurries. A chemical mechanical slurry stream contains inaddition to the solid slurry material, oxidizers like hydrogen peroxidein combination with acids and bases such as hydrochloric acid orammonium hydroxide. A chemical mechanical polishing tool is an exampleof a wafer processing apparatus used in semiconductor manufacturing.

To effect cross flow filtration, mass transfer, or heat transfer usingcontactors made from hollow tubes or porous hollow fibers, baffling iscommonly used to promote flow across the tubular elements. Variousdesigns for baffling have been detailed in the literature which improvethe transfer of heat and materials to the hollow tubes. U.S. Pat. No.5,352,361 teaches the art of baffling for hollow fiber gas to liquidcontactors. Such baffles are useful for polyethylene like hollow tubeswhere methods to pot and spin laminate baffles are easily implemented.Baffling of perfluronated tubes is not practical using this technique.U.S. Pat. No. 4,749,031 teaches baffling with perfluorinated bafflesthrough which individual hollow tubes are threaded. It is cumbersome,and expensive to manufacture exchange contactors using this technique.U.S. Pat. No. 4,360,059 describes a spiral heat exchanger prepared froma cast material such as aluminum. Such a method does not contemplate theuse of thermoplastics nor does it address the need for the substantiallyhigher surface area required for low thermally conductive thermoplasticmaterials.

U.S. Pat. No. 3,315,740 discloses a method of bonding tubes together byfusion for use in heat exchangers. Tubes of a thermoplastic material aregathered in a manner such that the end portions of the tubes are in acontacting parallel relationship. The end portion of the gathered tubesis placed within a sleeve having a thermoplastic internal surface andbeing rigid relative to the tubes. A fluid heated to a temperature atleast equal to the softening point of the thermoplastic material isintroduced into the interiors of the end portions of the tubes. Then apressure differential is imposed across the walls of the tubes so thatthe pressure within the tubes is greater than the pressure on theexterior surfaces of the tubes, thereby causing the tubes to be expandedand to be fused with the surfaces of the adjacent tubes. Such a methodproduces an irregular pattern of entrances to the hollows of the tubeseffecting non-uniform flow distribution to the tubes. Such a method alsorequires relatively thick walled tubing to provide sufficientthermoplastic to form a seal with the housing sleeve. It is notcontemplated to use such a potting method to form an end structure or aunified terminal end block, nor is it contemplated to braid the tubesand thermally set them prior to potting to provide enhanced flowdistribution.

Canadian Patent 1252082 teaches the art of making spiral wound polymericheat exchangers. Such a device requires mechanical fixtures to hold thetubes in place and as such requires a large volume of space.

U.S. Pat. No. 4,980,060 and U.S. Pat. No. 5,066,379 describe fusionbonded potting of porous hollow fiber tubes for filtration. Theinvention does not disclose the conditions required to effect fusionbonding of non-porous thermoplastic tubes for preparation of a unifiedterminal end block for use in phase and heat exchange. The inventiondoes not contemplate twisting or braiding of the hollow fibers nor doesit contemplate annealing the fibers prior to potting to effect astructure on the potted tubes for enhanced flow distribution.

Alan Gabelman and Sun-Tak Hwang in the Journal of Membrane Science,volume 159, pp 61-106, 1999 describe the importance of uniform fiberspacing for obtaining better mass transfer in hollow fiber contactors.The authors observe that hand built modules have more uniform fiberspacing but that the cost of such modules do not justify their highermanufacturing cost. Such arguments can be applied to hollow tube heatexchange and cross flow devices as well.

U.S. Pat. No. 5,224,522 describes a method and device for producingwoven hollow fiber tapes for use in exchange devices such as bloodoxygenators and heat exchangers. Such a device method requires expensiveand complicated weaving equipment to fix the fibers in a preferredrelationship in the tube mats.

Currently it is impractical to use thermoplastic heat exchangers forlarge heat loads, shell side liquid flow, or efficient shell side crossflow filtration because of the high expense and large size of devicesneeded. Metal heat exchangers are unacceptable for use in semiconductormanufacturing because of the corrosive nature of the chemicals and alsobecause of the need to eliminate metallic and particulate impuritiesfrom process liquids. What is needed is a thermoplastic apparatus forheat exchange, mass transfer, or cross flow filtration with high surfacearea, uniform fiber spacing, and minimal volume. The apparatus shouldeliminate the need for baffles.

SUMMARY OF THE INVENTION

The present invention provides for an apparatus with high surface areauseful in mass transfer, heat exchange, or cross flow particlefiltration. The apparatus is constructed of thermoplastic materials andcontains hollow thermoplastic fibers or hollow tubes fusion bonded intoa thermoplastic resin to form a unified terminal block. Optionally, theapparatus including the unified terminal block is fusion bonded into athermoplastic housing which has fluid inlet and fluid outlet connectionsfor the process and working fluids to be contacted across the hollowfibers or hollow tubes. A manufacturing method for the apparatus isprovided and described. A method of use of the apparatus is alsoprovided and described.

In one embodiment the hollow tubes in the apparatus are braided,plaited, or twisted together to create a cord of the tubes or fibersprior to fusion bonding into the thermoplastic resin to form a unifiedterminal block. Such cords provide enhanced flow distribution of fluidthrough the apparatus without the need for baffling. A high packingdensity of hollow tubes or cords is achieved with this invention.

In another embodiment the cord containing the hollow tubes or fibers isannealed in an oven to set the shape of the twist, plait, or braid ofthe hollow tubes or fibers in place prior to the fusion bonding process.Alternatively, the hollow tube or cord can be wrapped around a rod,another hollow tube, or a template and the shape of the hollow tube orcord set by thermal annealing with the template. The braided or twistedcord can be wound on a rack and thermally annealed setting the cord'splait, geometry, and length. The braided or twisted cords are removedfrom the rack as a bundle of continuous cord which is then fusion bondedinto a thermoplastic resin to form a unified terminal block. In analternative embodiment, the annealed cord can be unwrapped to giveindividual non-circumferential hollow tubes or fibers. These individualhollow tubes are fusion bonded into a thermoplastic resin well as abundle. Optionally, the annealed cord or individual non-circumferentialhollow tubes or fibers in the unified terminal block are fusion bondedto a thermoplastic housing which has fluid inlet and fluid outletconnections for the process and working fluids to be exchanged by theapparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (A-D) are schematic diagrams illustrating examples of a twistedand braided hollow tubes.

FIG. 2A is a schematic diagram, in cross section, of an exchangeapparatus with non-circumferential hollow tubes fused in a thermoplasticresin.

FIG. 2B is a schematic diagram, in cross section, of an exchangeapparatus with non-circumferential hollow tubes fused in a thermoplasticresin having fluid inlet and outlet connections.

FIG. 2C is a schematic diagram, in cross section, of an exchangeapparatus with non-circumferential hollow tubes fused in a thermoplasticresin having fluid inlet and outlet connections and a housing with fluidconnections.

FIG. 3 is a schematic diagram, in cross section, of an exchangeapparatus with twisted hollow tubes fused in a thermoplastic resinhaving fluid inlet and outlet connections and a housing with fluidconnections.

FIG. 4 is a schematic diagram, in cross section, of an exchangeapparatus with braided hollow tubes fused in a thermoplastic resinhaving fluid inlet and outlet connections and a housing with fluidconnections.

FIG. 5 is a schematic diagram illustrating an end view of an exchangeapparatus with braided hollow tubes fused in a thermoplastic resinhaving fluid inlet and outlet connections and a housing with fluidconnections.

FIG. 6 is a table detailing the performance of the heat exchangersdescribed in the Example 2 and Example 3.

FIG. 7 is a photomicrograph of hollow tube ends fusion bonded into athermoplastic resin using the method of this invention.

FIG. 8 is a Table detailing the performance of a twenty tube heatexchanger described in Example 6.

FIG. 9 is a Table detailing the performance of a 680 tube heat exchangerdescribed in Example 7.

DESCRIPTION OF SPECIFIC EMBODIMENTS

This invention relates to an apparatus for heat and mass transferoperations as well as other phase separation applications. The presentinvention also describes a method for making a unified terminal endblock, fusion bonded exchange apparatus comprising braided or twistedthermoplastic hollow tubes or hollow fibers. A cord is referred to inthe practice of this invention as one or more fibers and or tubes whichhave been twisted together, plaited, or braided to form a unit which canbe potted or fused into a well of a thermoplastic resin by the method ofthis invention. The fusion bonding is performed with a thermoplasticpolymer. While the present invention will be described with reference tonon-porous poly(tetrafluoroethylene-co-perfluoromethylvinylether) hollowtubes, it is to be understood that the present invention can be madeusing a variety of thermoplastic tubes and or porous fiber membraneswhich will hereafter referred to in general as hollow tubes. Further,while the present invention is described with reference to twisted pairsof poly(tetrafluoroethylene-co-perfluoromethylvinylether) hollow tubes,it is to be understood that the present invention can be made using avariety of numbers of hollow tubes or hollow fibers which are twisted,woven, plaited, or braided to form what are hereafter referred to ascords. Finally, while the present invention is described with respect toan apparatus for heat exchange, similar devices utilizing porous hollowtubes or hollow fibers can be made for use in mass transfer and crossflow filtration applications.

For purposes of this invention, a single, un-wrapped annealed tube isconsidered a non-circumferential tube. Non-circumferential tubes aretubes with external dimensions that are not continuously circumferentialon a longitudinal axis moving from one end portion of the tube to theother. Examples include, but are not limited to, a helical coil, apermanently twisted hollow circular tubing such as the single, unwrappedannealed fiber or a tube that is extruded in such condition, atriangular shaped tube or fiber, a rectangular shaped tube or fiber, ora square shaped tube or fiber.

The braid, plait, twist, or non-circumferential geometry of the hollowtubes or fibers provides for enhanced fluid distribution across andwithin the hollow tubes. The device provides high fluid contacting areain a small volume without the need for baffles. The unitary or unifiedterminal block construction of the apparatus with chemically inertmaterials of construction eliminates the need for O-rings and permitsuse of operation of the device at elevated temperatures and with avariety of fluids.

Two or more hollow tubes can be plaited, twisted or braided into a cordmanually or by use of commercially available winding and braidingequipment. In the practice of this invention a plurality of hollow tubescan be woven together to form mats of hollow tubes. For purposes of thisdisclosure and appended claims the terms mat and cord are usedinterchangeably. The number of twists of tube per foot in a cord isdefined by the distance λ₁ as illustrated in FIG. 1A. In FIG. 1A twotubes are shown twisted together, however any number of tubes can betwisted together to form a cord. In FIG. 1A the parameter λ₁ describesthe distance from crest to crest or bend to bend of the hollow tube 10twisted with hollow tube 12. A smaller value of the parameter λ, forexample λ₂ in FIG. 1B, illustrates a greater number of twists or bendsbetween hollow tubes 14 and 16. More than two hollow tubes can bebraided together to form a cord. For braided hollow tubes, asillustrated for individual tubes 18, 20, and 22 in FIG. 1C, a measure ofcord tightness is described by the parameter λ₃. Individual hollow tubes24, 26, and 28, as shown in FIG. 1D, are more tightly braided and so theparameter λ₄ is correspondingly smaller than λ₃. The value of λ canrange from 1 per foot to 50 per foot with a preferred range of 5-25crests or bends per foot. The number of hollow tubes twisted or braidedtogether to form a cord can range from 2 to 100, but is more preferablyfrom 2 to 10 hollow tubes.

The invention is described in more detail with reference to FIG. 2A. Asillustrated schematically in FIG. 2A, a portion of each end ofindividual thermoplastic non-circumferential tubes 36, 38, and 40 arefusion bonded in a fluid tight matter with a thermoplastic resin to formtwo unitary end or unified terminal end block structures 32 and 34. Anynumber of thermoplastic hollow tubes can be fused into the thermoplasticresin. FIG. 2B illustrates a cross section of an exchange apparatusfurther comprising fluid connection ports 40 and 42 bonded to theunified terminal end blocks 34 and 32 with end caps 44 and 46. The endcaps and fluid connectors allow a first fluid from a source, not shown,to flow through the hollow tubes 36, 38, and 40. The two sides of thetypical hollow tube or hollow fiber 38 of this invention are furthercharacterized by the surfaces 37 and 39. FIG. 2C illustrates a crosssection of an exchange apparatus further comprising a housing 52 bondedto unified terminal end blocks 32 and 34 and having one or more fluidconnector ports 48 and 50.

In FIG. 3 an embodiment of the exchange apparatus is illustrated furthercomprising cords of twisted hollow tubes. The cords in this illustrationare comprised of hollow tubes 54 and 56, 58 and 60, and 62 and 64. Aportion of the ends of each cord are fusion bonded in a fluid tightmanner with a thermoplastic resin to form the unified terminal endblocks 32 and 34. The apparatus can have optional housing 52 and endcaps 44 and 46 bonded to the unified terminal end blocks. In FIG. 3 atleast one fluid flow distributor 66 can optionally be press fit,threaded, or bonded into on or more of the housing fluid connectionports 48 and 50.

In FIG. 4 an embodiment of the exchange apparatus is illustrated furthercomprising cords of braided hollow tubes. The cords in this illustrationare comprised of three or more hollow tubes braided together to formcords illustrated by 70 and 72. The ends of each cord are fusion bondedin a fluid tight manner with a thermoplastic resin to for the unifiedterminal end blocks 32 and 34. The apparatus can have optional housing52 and end caps 44 and 46 bonded to the unified terminal end blocks. InFIG. 4 at least one fluid flow distributor 66 can optionally be pressfit, threaded, or bonded into on or more of the housing fluid connectionports 48 and 50. An end view of the exchange apparatus shown in FIG. 4is illustrated schematically in FIG. 5.

With reference to FIG. 3, the operation of one embodiment of the presentinvention as a heat exchanger will be described. A first fluid entersthe exchange apparatus through fluid connection port 42 and enters thehollow tubes at openings 61 in the unified terminal end block 32. Fluidflows through the interior or lumen of the hollow tubes and exits thetubes through the unified end block 34 at exit openings 63. The firstfluid exits the exchange apparatus through fluid connection port 40. Asecond fluid enters the exchange apparatus through housing fluid port 48and optional flow distributor 66. The first fluid is separated from asecond fluid by the two surfaces and wall of the hollow tube. The secondfluid enters the housing through connection 48 and substantially fillsthe space between the inner wall of the housing and the outer diametersof the fibers. Energy is transferred between the first and second fluidsthrough the thermoplastic hollow tube walls. The second fluid exits thehousing through the fluid connector port 50. Examples of fluids includeliquids, vapors of liquids, gases, and super critical fluids.

Manufacturers produce membranes from a variety of materials, the mostgeneral class being synthetic polymers. An important class of syntheticpolymers are thermoplastic polymers, which can be flowed and molded whenheated and recover their original solid properties when cooled. As theconditions of the application to which a tube or membrane is being usedbecome more severe, the materials that can be used becomes limited. Forexample, the organic solvent based solutions used for wafer coating inthe microelectronics industry will dissolve or swell and weaken somepolymeric tubes and membranes. The high temperature stripping baths inthe same industry consist of highly acid and oxidative compounds, whichwill destroy membranes and tubes made of common polymers.

Hollow tubes made from thermoplastics with outside diameters rangingfrom 0.007 to 0.5 inches, and more preferably 0.025 to 0.1 inches indiameter, and wall thickness ranging from 0.001 to 0.1 inches,preferably 0.003 to 0.05 inches in thickness, are useful in the practiceof this invention. The tubes can be used individually, or the tubes canbe combined by braiding, plaiting, or twisting them to form cordscomprised of multiple hollow tubes.

Examples of perfluorinated thermoplastics or their blends which areuseful in the practice of this invention include but are not limited to[Polytetrafluoroethylene-co-perfluoromethylvinylether], (MFA),[Polytetrafluoroethylene-co-perfluoropropylvinylether], (PFA),[Polytetrafluoroethylene-co-hexafluoropropylene], (FEP), and[polyvinylidene fluoride], (PVDF). Both PFA Teflon® and FEP Teflon®thermoplastics are manufactured by DuPont, Wilmington, Del. Neoflon® PFAis a polymer available from Daikin Industries. MFA Haflon® is a polymeravailable from Ausimont USA Inc. Thorofare, N.J. Preformed MFA Haflon®and FEP Teflon® tubes are available from Zeus Industrial Products Inc.Orangebury, S.C. Other thermoplastics or their blends which are usefulin the practice of this invention include but not limited topoly(chlorotrifluoroethylene vinylidene fluoride), polyvinylchloride,polyolefins like polypropylene, polyethylene, polymethylpentene, ultrahigh molecular weight polyethylene, polyamides, polysulfones,polyetheretherketones, and polycarbonates.

Hollow thermoplastic tubes can be impregnated with thermally conductivepowders or fibers to increase their thermal conductance. Examples ofuseful thermally conductive materials include but are not limited toglass fibers, metal nitride fibers, silicon and metal carbide fibers, orgraphite. The thermal conductivity of the hollow thermoplastic tubes orimpregnated thermoplastic hollow tubes useful in this invention isgreater than about 0.05 watts per meter per degree Kelvin.

Hollow tubes useful in the practice of this invention for particlefiltration and mass transfer applications such as gas contacting, liquiddegassing, and pervaporation include hollow fiber membranes. Suitablemembranes include hollow fibers made from[Polytetrafluoroethylene-co-perfluoropropylvinylether], (PFA), or ultrahigh molecular weight polyethylene, both available from MykrolisCorporation, Billerica, Mass.

In a preferred embodiment the twisted, plaited, or braided tube form acontinuous cord. The cord can be wound around a rectangular metal frame,as described in WO 00/44479, the distance between parallel sidesdefining the length of the exchange device. The coiled cord on the metalframe is placed in an oven below the melting point of the hollow tubes.The tubes are thermally annealed at a temperature below their meltingpoint and then cooled to set the crests or bends in the braided,plaited, or twisted tubes into the cord. Annealing of the cord tubesoccurs below the melting point at a temperature usually less than 250degrees Celsius, more preferably from 100 to 200 degrees Celsius, andfor a time ranging from 15 to 60 minutes, and more preferably for 30minutes. In an alternative embodiment the twisted, plaited, or braidedtubes can be annealed on a spool.

In another embodiment the braided or twisted tubes can be thermallyannealed in a first step and then the individual tubes separated fromeach other after cooling to form self supporting helical shaped ornon-circumferential shaped single tubes. Thermal annealing sets thecrests and bends of the hollow tube so that the individual hollow tubesor cords can be separated and handled without straightening.

In one embodiment of the present invention, the thermally annealed andset cords of hollow tubes can be joined by the method described in U.S.Pat. No. 3,315,750 included herein by reference in its entirety. Thecords can also be joined to each other and to the housing by theinjection molding method described in European Patent Application 0 559149 A1 included herein by reference in its entirety. In a preferredembodiment, the method described in U.S. patent application 60/117,853,filed Jan. 29, 1999 and WO 00/44479, and incorporated herein in itsentirety by reference is useful in the practice of the currentinvention.

The term unified terminal end block or unitary end structure in thepractice of this invention is meant to describe a mass or well of athermoplastic resin into which one or more hollow tubes or cords havebeen bonded or fusion bonded. FIG. 7 illustrates an example of hollowtubes fusion bonded to a thermoplastic resin to form a unified terminalend block structure and hollow tubes not fusion bonded to athermoplastic resin. U.S. patent application No. 60/117,853 describes ahollow fiber bonded to a thermoplastic resin. Optionally thermoplasticend caps having fluid connector ports or a thermoplastic housing may befusion bonded to the one or more of the unified terminal end blocks. Forpurposes of illustrating the present invention, a unified terminal endblock comprising hollow tubes, a thermoplastic resin, and athermoplastic housing is described. The housing to form a single entityconsisting solely of perfluorinated thermoplastic materials is preparedby first pretreating the surfaces of both ends of the housing before thepotting and bonding step A unified terminal end block end structure, bywhich is meant that the braided or twisted tubes and the potting arebonded to the housing to form a single entity consisting solely ofperfluorinated thermoplastic materials is prepared by first pretreatingthe surfaces of both ends of the housing before the potting and bondingstep. This is accomplished by melt-bonding the potting material to thehousing. The internal surfaces on both ends of the housing are heatedclose to their melting point or just at the melting point andimmediately immersed into a cup containing powdered[Polytetrafluoroethylene-co-perfluoromethylvinylether] thermoplasticpotting resin available from Ausimont USA Inc. Thorofare, N.J. Since thesurface temperature of the housing is higher than the melting point ofthe potting resins, the potting resin is then fused to the thermoplastichousing. The housing is then taken out and polished with a heat gun tofuse any excess un-melted thermoplastic powder. It is preferred thateach end of the tube be treated at least twice with this pre-treatment.

The annealed twisted hollow tube cords are inserted into apoly(tetrafluoroethylene-co-perfluoro(alkyvinylether)), Teflon® PFA, orMFA shell tube. The shell tube optionally has fluid fittings fusionbonded to its surface to form an inlet and an outlet ports. The packingdensity of the tube cords within the shell tube should be in the rangeof from 3-99 percent by volume, and more preferably 20-60 percent byvolume.

Potting and bonding of the tube cords into the housing can be done in asingle step. The preferred thermoplastic resin potting material isHyflon® MFA 940 AX resin, available from Ausimont USA Inc. Thorofare,N.J. The method comprises vertically placing a portion of a bundle ofthe annealed and twisted hollow tube cord lengths with at least oneclosed end into a temporary recess made in a pool of moltenthermoplastic polymer held in a container. The hollow tubes are held ina defined vertical position, maintaining the thermoplastic polymer in amolten state so that it flows into the temporary recess, around thehollow tubes and vertical up the fibers, completely filling theinterstitial spaces between fibers with the thermoplastic polymer. Atemporary recess is a recess that remains as a recess in the moltenpotting material for a time sufficient to position and fix the bundle ofhollow tubes in place and then will be filled by the moltenthermoplastic. The temporary nature of the recess can be controlled bythe temperature at which the potting material is held, the temperatureat which the potting material is held during hollow tube bundleplacement, and the physical properties of the potting material. The endof the hollow tube can be closed by sealing, plugging, or in a preferredembodiment, by being formed in a loop.

Once the first end of the device has been potted and fused into aunified terminal end block comprising the hollow tubes, housing andthermoplastic resin, the second end of the device is potted. The processinvolves heating the potting resins in a heating cup with an externalheating block or other heat source at a temperature in the range of fromabout 265 C to around 285 C, with a preferred range of from about 270 Cto around 280 C, until the melt turns clear and is free of trappedbubbles. A rod is inserted into the melt to create a recess or cavity.The housing and the hollow tube bundle are then inserted into thecavity. It is important to note that at this point neither the hollowtube bundle nor the housing touches the potting resin. The melted resinwill flow by gravity to fill the voids over time to pot the hollow tubesand bond to the housing simultaneously. After the potted ends arecooled, they are then cut and the lumen of the hollow tubes exposed. Thepotted surfaces are then polished further using a heat gun to melt awayany smeared or rough potted surfaces. For module with a large number ofhollow tubes, such as 2000 or more, it is possible that the module maypotting defects which can be repaired using a clean soldering iron tofuse and close the damaged areas.

Another embodiment of this invention is useful for potting helical cordscomposed of hollow tubes. Each end of the twisted or braided hollowtubes are potted in a metal mold in a first step. The mold is slightlysmaller than the inner diameter of the shell tube and can be made fromaluminum or nickel or similar alloys. After potting and cooling, themold is removed. The ends of the hollow tubes in the unified terminalend blocks are opened by cutting as described above. After both ends ofthe hollow tubes have been potted, the formed unified terminal end blockstructures are inserted into a pretreated MFA or PFA shell housing tube,or end caps, and the unified terminal end block fused to the housingtube or end caps in a short heating process.

In a preferred embodiment of this invention illustrated in FIG. 3, atleast one thermoplastic tube 66 is inserted into at least one of thefluid fittings 48 on the shell side of the exchange apparatus. It ispreferred that the tube be placed into a portion of the tube bundlenearest the fitting. The tube can be thermally bonded to the housing orpress fit into the shell fittings. The tube provides for improved flowdistribution of fluid in the device.

Fluid fitting useful for connecting the apparatus of this invention tosources of working and process fluid include but are not limited toFlaretek®, Pillar®, Swagelock®, VCO®, standard pipe thread fittings, orbarb fittings. In a preferred embodiment two fluid connections areprovided for the process fluid; one inlet connection for flow of fluidinto the apparatus and one outlet connection for flow of fluid out fromthe apparatus. The process fluid may flow through the tubes or acrossthe outside of the tubes. The inlet and outlet connections for theprocess fluid may be bonded to the unified terminal end blocks bywelding, threading, flanging, or fusion bonding to the thermoplastic. Ifa housing is provided for the exchange apparatus, the inlet connectionsfor the process fluid may be bonded to the housing and or unifiedterminal end block by welding, threading, or flanging. In a preferredembodiment the connections are fusion bonded to the housing and or theunified terminal end block. One or more fluid connections may beprovided for flow of working fluid through the housing or for flow offiltered liquid out of the housing. The one or more connections for flowof working fluid or filtered fluid through the housing may be bonded tothe housing by welding, threading, or flanging to the housing. In apreferred embodiment the connections are fusion bonded to the housing.

General Procedure 1

Preformed hollow MFA tube tubes with 0.047 inch inside diameter and0.006 inch thick wall thickness were obtained from Zeus IndustrialProducts Inc. Orangebury, S.C. Cords for potting were made by handtwisting pairs of these hollow MFA tubes to obtain about 12 turns perfoot of cord. A single cord was wrapped around a metal frame 8 incheswide and 18-27 inched long; it was possible to make about 75 wraps ofthe cord on the metal frame. The frame and wrapped cords were annealedin an oven for 30 minutes at 150 degrees Celsius. About 75 loops of cordeach measuring 18-27 inches in length were obtained from the rack afterannealing. Cord from a single rack or from multiple racks were gatheredand placed into a previously heat treated and MFA coated PFA tubemeasuring 16-25 inches in length. The inside diameter of the tubes was1-2.25 inch and ¼″ FlareTek® fluid fittings were bonded approximately 2inches from each end of the PFA tube. Each end of the device was pottedusing Hyflon® MFA 940 AX resin, obtained from Ausimont USA Inc.Thorofare, N.J., for about 40 hours at 275° C. Cool down of each endafter 40 hours of potting was controlled to a rate of 0.2 C.°/min to 150C.°. The unified terminal block ends were cleared of resin and thehollow tubes opened by machining the end portion of the potted deviceusing a lathe or knife. Fluid fittings for the potted exchanger weremade by scoring a pipe thread onto each end of the tube or by thermallyfusing an end cap onto the tube.

EXAMPLE 1

A prototype heat exchanger having a housing with a 1 inch insidediameter PFA tube was prepared by Procedure 1 except that the tubes werenot twisted or annealed. The device contained 150 tubes of straight MFAtube measuring 15 inches in length.

The prototypes was tested under the following conditions. Hot water at atemperature of 63° C. was fed into the tube side of the device at a flowrate of approximately 1750 ml/min. Cold water at a temperature of 19° C.was fed into the shell side of the device at a flow rate ofapproximately 1070 ml/min. The hot and cold water paths flowedcountercurrent to one another. The inlet and outlet temperatures and theflow rates were recorded every five minutes for the tube and shell sidefluid streams for one hour. The results from this experiment aredetailed in Table 1 shown in FIG. 6. Under these conditions the coldwater was heated from 18.9° C. to 38.8° C. and a total of 1486 watts ofenergy was exchanged between the two fluids.

EXAMPLE 2

A prototype heat exchange apparatus having a housing with a 1 inchinside diameter PFA tube was prepared by Procedure 1 except that itcontained about 150 hollow MFA tubes twisted together with about 12twists per foot. The twisted cords were annealed on a metal rack toyield approximately 75 cords measuring about 15 inches in length.

The prototype was tested under the following conditions. Hot water at atemperature of 55° C. was fed into the tube side of the device at a flowrate of approximately 1650 ml/min. Cold water at a temperature of 19° C.was fed into the shell side of the device at a flow rate ofapproximately 1070 ml/min. The hot and cold water paths flowedcountercurrent to one another. The inlet and outlet temperatures and theflow rates were recorded every five minutes for the tube and shell sidefluid streams for one hour. The results from this experiment aredetailed in Table 1 in FIG. 6. Under these conditions the cold water washeated to from 18.9° C. to 44.0° C. and a total of 1874 watts of energywas exchanged between the two fluids.

EXAMPLE 3

This prospective example shows how a wafer processing tool including theexchange apparatus of this invention can be used to heat liquids usedfor cleaning semiconductor wafers.

An exchange apparatus having about 650 twisted hollow MFA tubes, 325pairs, can be thermally annealed and fusion bonded in a 2 inch insidediameter PFA tube using the methods of Procedure 1. The length of thedevice can be about 18 inches and has a liquid volume of about 300milliliters. The device is part of a wafer processing tool and isconnected at its inlet fluid connection to an in-line to a source ofaqueous 10% hydrochloric acid containing about 1 percent by volumehydrogen peroxide. The outlet of the exchange device is connected to avalve, optional stop suck back valve, and nozzle for dispensing theaqueous acid solution onto a substrate to be cleaned. One of the fluidinlet connections on the shell side of the exchange device is connectedin-line to a source of hot water. Hot deionized water is commonlyavailable in a semiconductor factory at a temperature of about 75degrees Celsius. The heated water passing through the shell side of theexchange device heats the acid solution contained within the tubes ofthe exchange apparatus. After a variable time of no fluid flow, thevalve at the outlet of the exchange device is opened and heated aqueousacid and oxidant is dispensed onto the wafer where it is used to cleanthe wafer. The valve is closed and liquid acid and oxidant flows intothe hollow tubes of the exchange apparatus where it is heated for thenext dispense.

EXAMPLE 4

This prospective example shows how an exchanger for cross flowfiltration may be made utilizing thermally annealed, plaited, poroushollow PFA tubes.

A prototype filtration device having a housing with a 1 inch diameterPFA tube was prepared by Procedure 1 except that 150 hollow porous PFAfibers having a 550 micron outside diameter, available from MykrolisCorporation, Billericia, Mass., are substituted for the non poroushollow MFA tubes. The hollow fibers can be plaited 3 per strand and canbe wound on a rack measuring 15 inches in length. The plaited and woundhollow fibers can be thermally annealed at about 150 Celsius to set theplait and length of the hollow fibers. The thermally annealed andplaited hollow fibers are assembled into an apparatus according to themethod disclosed in WO 0044479.

The housing for this device contains inlet and outlet port connectionsfor flow of a fluid containing insoluble suspended materials likecolloids, gels, or hard particles. Examples of fluids containingsuspended solid particles include alumina in a chemical mechanicalpolishing slurries, examples of colloids in fluids can include silica.The fluid containing the insoluble suspended material flows through theinsides of the porous hollow fiber tubes. The housing has a single fluidflow port connection for flow of filtered liquid away from the housing.A portion of the liquid containing the suspended solids flows across theplaited porous hollow tubes; some of the solids are retained by theporous membrane and a portion of filtered liquid flows through themembrane and out of the fluid port on the housing.

EXAMPLE 5

This prospective example shows how an exchange apparatus for masstransfer of a gas into a liquid may be made utilizing thermallyannealed, plaited, porous hollow PFA tubes.

A prototype filtration device having a housing with a 1 inch diameterPFA tube can be prepared by Procedure 1 except that 150 hollow porousPFA fibers having a 550 micron outside diameter, available from MykrolisCorporation, Billericia, Mass., are substituted for the 150 hollow MFAtubes. The hollow fibers can be plaited 3 per strand and can be wound ona rack measuring 15 inches in length. The plaited and wound hollowfibers can be thermally annealed at about 150 C. to set the plait andlength of the tubes. The thermally annealed and plaited hollow fiberscan be assembled into an apparatus according to the method disclosed inWO 0044479.

The housing for this device can have inlet and outlet port connectionsfor flow of deionized water through the insides of the porous hollowfiber tubes. One of the housing's two ports can be used for connectionto a source of ozone gas generated by an ozone generator, for exampleAstex 8400 ozone generator available from Astex, Woburn, Mass. The ozonegas dissolves in the water by permeating through the porous plaitedhollow PFA tubes. Excess ozone gas is vented through the housing'ssecond port. Water exiting the insides of the tubes contains ozone gasdissolved in the water. This ozonated water is useful for cleaningwafers using a modified RCA cleaning processes.

EXAMPLE 6

This example illustrates a heat exchange apparatus of this inventionwith twenty thin walled hollow PFA tubes. The device was used to heatflowing water in-line.

A 0.5 inch OD PFA tube of length 17 inches was used as a housingconduit. The housing conduit had inlet and outlet ports. The housingconduit was fusion bonded using PFA potting material at each end totwenty six 1.05 mm ID PFA tubes with wall thickness 0.15 mm. Two J-typethermocouples were positioned in separate flow through housings. Onethermocouple was connected to the inlet port of the exchange apparatushousing conduit and the second thermocouple was connected to the outletport of the heater device housing conduit. In operation process waterflows through the inlet thermocouple housing, into the exchangerapparatus housing, and through the hollow tubes. Working or exchangefluid passed through an inlet thermocouple housing and into the shellside of the housing in a counter current fashion where it contacted theoutsides of the hollow tubes. The exchange or working fluid then passesthrough the outlet port on the shell side of the housing conduit andthrough a second outlet thermocouple housing. Process water flowingthrough the exchange apparatus tubes exits the tubes through a secondoutlet thermocouple housing. With a flow rate of 1000 milliliters perminute of water at a temperature of about 16 degrees Celsius flowinginto the shell side of the device, water flowing into the tubes at atemperature of 55.5 degrees Celsius and a flow rate of 260 millilitersper minute was cooled to 33.1° C. on exiting the tubes. The performanceof this apparatus at different tube side flow rates is summarized inFIG. 8.

EXAMPLE 7

This example illustrates a heat exchange apparatus of this inventionwith 680 thin walled hollow MFA tubes. The device was used to coolflowing water in-line.

A prototype heat exchange apparatus having a PFA housing with a 2.25inch inside diameter 32 inch length was prepared by Procedure 1 exceptthat it contained about 680 hollow MFA tubes twisted together with about12 twists per foot. The twisted cords were annealed on a metal rack toyield cords measuring about 34 inches in length. Inlet fluid fittings onthe housing shell side were ½″ Flaretek®; they were 27 inches apart and2.5 inches from the ends of the device. The housing fluid fittings fortube side flow were ¾″ Flaretek® and were fusion bonded to the housingtube.

The prototype was tested under the following conditions. Hot water at atemperature of 70.1° C. was fed into the tube side of the device at aflow rate of approximately 4.4 liters per minute. Cold water at atemperature of 14.5° C. was fed into the shell side of the device at aflow rate of approximately 6.6 liters per minute. The hot and cold waterpaths flowed countercurrent to one another. The inlet and outlettemperatures and the flow rates were recorded using an Agilent datalogger. The results from this experiment are detailed in the Table inFIG. 9. Under these conditions the hot water in the tubes was cooledfrom 70.1° C. to 22.9° C. and a total of 14,400 watts of energy wasexchanged between the two fluids. The performance of this apparatus atother flow rates is summarized in FIG. 9.

1-26. (canceled)
 27. An exchange apparatus comprising: a perfluorinatedthermoplastic housing; cords of two or more perfluorinated thermoplastichollow tubes, said cords having a shape set by thermal annealing, theperfluorinated hollow tubes in said cords having a first end portion anda second end portion and hollows passing therebetween; the first endportions of said perfluorinated thermoplastic hollow tubes being fusionbonded at least at a periphery of said perfluorinated thermoplastichollow tubes through a perfluorinated thermoplastic resin to form afirst unified terminal end block in which the end portions of saidperfluorinated thermoplastic hollow tubes are fluid tightly bondedtogether in a fused fashion with the perfluorinated thermoplastic resin;said second end portions of said perfluorinated thermoplastic hollowtubes being fusion bonded at least at a periphery of said perfluorinatedthermoplastic hollow tubes through a perfluorinated thermoplastic resinto form a second unified terminal end block in which the end portions ofsaid perfluorinated thermoplastic hollow tubes are fluid tightly bondedtogether in a fused fashion with the perfluorinated thermoplastic resin;said first unified terminal end block and said second unified terminalend block having through hole communication with the hollows of theunbonded portions of said perfluorinated thermoplastic hollow tubes;said first unified terminal end block having a first fluid inletconnection to supply a first fluid to said perfluorinated thermoplastichollow tubes and said second unified terminal end block having a firstfluid outlet connection to remove said first fluid from saidperfluorinated thermoplastic hollow tubes; said perfluorinatedthermoplastic housing fusion bonded with said perfluorinatedthermoplastic resin to form a single entity of fusion bondedperfluorinated thermoplastic materials; said perfluorinatedthermoplastic housing having first housing port wherein a second fluidenters the exchange apparatus and a second housing port wherein saidsecond fluid exits the housing.
 28. The apparatus of claim 27, wherein apacking density of said perfluorinated thermoplastic hollow tubes rangesfrom 20 to 60 percent by volume.
 29. The apparatus of claim 27, whereinsaid perfluorinated thermoplastic hollow tubes are comprised of athermoplastic or a blend thereof chosen from the group consisting ofpolytetrafluoroethylene-co-perfluoromethylvinylether,polytetrafluoroethylene-co-perfluoropropylvinylether,polytetrafluoroethylene-co-hexafluoropropylene, and polyvinylidinefluoride.
 30. The apparatus of claim 27, wherein the perfluorinatedthermoplastic hollow tubes are non-porous.
 31. The apparatus of claim 27wherein said perfluorinated thermoplastic hollow tubes are impregnatedwith a thermally conductive material.
 32. A method comprising: flowing afirst fluid on a first side of cords of two or more perfluorinatedthermoplastic hollow tubes, said cords having a shape set by thermalannealing, the perfluorinated hollow tubes in said cords having a firstend portion and a second end portion and hollows passing therebetween;the first end portions of said perfluorinated thermoplastic hollow tubesbeing fusion bonded at least at a periphery of said perfluorinatedthermoplastic hollow tubes through a perfluorinated thermoplastic resinto form a first unified terminal end block in which the end portions ofsaid perfluorinated thermoplastic hollow tubes are fluid tightly bondedtogether in a fused fashion with the perfluorinated thermoplastic resin;said second end portions of said perfluorinated thermoplastic hollowtubes being fusion bonded at least at a periphery of said perfluorinatedthermoplastic hollow tubes through a perfluorinated thermoplastic resinto form a second unified terminal end block in which the end portions ofsaid perfluorinated thermoplastic hollow tubes are fluid tightly bondedtogether in a fused fashion with the perfluorinated thermoplastic resin;said first unified terminal end block and said second unified terminalend block having through hole communication with the hollows of theunbonded portions of said perfluorinated thermoplastic hollow tubes;said first unified terminal end block having a first fluid inletconnection to supply said first fluid to said first side of saidperfluorinated thermoplastic hollow tubes and said second unifiedterminal end block having a first fluid outlet connection to remove saidfirst fluid from said first side of said perfluorinated thermoplastichollow tubes; a perfluorinated thermoplastic housing fusion bonded bysaid perfluorinated thermoplastic resin to form a single entity offusion bonded perfluorinated thermoplastic materials; flowing a secondfluid on a second side of said perfluorinated thermoplastic hollowtubes; said perfluorinated thermoplastic housing having first housingport wherein said second fluid enters the exchange apparatus and asecond housing port wherein said second fluid exits the housing; andtransferring energy between said first and said second fluids throughthe wall of the perfluorinated thermoplastic hollow tubes.
 33. Themethod of claim 32 wherein said first fluid is a photoresist, anantireflective coating, a resist stripper, or a photoresist developer.34. The method of claim 32 wherein said first fluid is a liquid spin ondielectric.
 35. The method of claim 32 wherein said first fluid is afluid comprising copper ions.
 36. The method of claim 32 wherein saidfirst fluid is chosen from the group consisting of an acid, a base, anoxidizer, and mixtures thereof.
 37. The method of claim 32 wherein saidfirst fluid is an organic liquid.
 38. The method claim 32 wherein saidsecond fluid is chosen from the group consisting of an inert gas, water,polyethylene glycol compositions, and steam.